Device for protecting the knee joint that is able to engage with a ski boot

ABSTRACT

A device for protecting the knee joint of a skier, the device being for installing on a ski boot having a footwear portion surmounted by a collar, the device having first connector designed to be fastened to the collar of the boot and a shell designed to cover the front of the tibia of the skier, the shell extending between a high portion for being situated level with the skier&#39;s knee and a low portion covering a portion of the collar of the boot, the shell supporting, on its high portion, lateral flanges suitable for being put into contact with the knee on either side of the knee being in contact at least with the condyles of the femur of the skier.

BACKGROUND OF THE INVENTION

The present invention relates to the general field of devices for protecting the knee joint and suitable for co-operating with a ski boot, where such a boot conventionally comprises a footwear portion surmounted by a collar.

Such a device is for use by a competitive and/or recreational skier. Nowadays, every year in France, there are about 17,000 knee sprains with or without broken ligaments as a result of falls while skiing. This gives rise to treatments that are lengthy and to side effects that are often major. Direct and indirect costs for society are very considerable, being evaluated at 300 million euros (M

) per year.

It is known that the knee can withstand relatively high stress so long as it is of very short duration. In contrast, lesions can appear in the ligaments at low levels of force if the stress is maintained for a duration that is long enough.

Devices for protecting the knee joint seek to reduce the risk of tearing a ligament in a skier's knee. Proper operation of such devices requires them to protect the joint while it is being very highly stressed, while also allowing freedom of movements during normal skiing.

In general, the only safety element in existence for protecting a skier's knee is the ski binding. The principle consists in releasing the boot when the jaws of the binding are subjected to torque exceeding a certain trigger threshold.

In practice, that situation leads to two main problems: a competitive or an experienced skier will tend to set the trigger threshold of the bindings very high. This avoids untimely triggering when edging hard. In contrast, falling is much more dangerous since the bindings will have greater difficulty in releasing the boot.

A beginner skier might end up falling very slowly. The trigger threshold is then never reached, even if it is set low enough.

The invention seeks to limit the risks of knee injuries in particular sprains and torn ligaments associated with excessive relative axial rotation of the tibia or femur and/or excessive shear in the X′Y′ plane.

Movements in rotation and in translation between the tibia and the femur are measured relative to three axes at the knee. For this purpose, if a local frame of reference is defined tied to the top end of the tibia: the substantially horizontal X′Y′ plane is the plane of the tibial plateau; with the axis Z′ being the longitudinal axis of the tibia perpendicular to the plane of the tibial plateau, and thus substantially vertical.

In this frame of reference, the following movements in rotation and in translation can take place as shown in FIG. 11:

-   -   axial rotation of the tibia at the knee: this rotation         corresponds to the angle between two transverse vectors of the         tibia and of the femur, one at the tibial plateau and the other         between the two condyles of the femur, this rotation being         projected onto the tibial plateau (plane X′Y′) (FIG. 11A);     -   rotation in lateral flexing: this corresponds to the angle         between the two transverse vectors of the tibia and the femur,         but in the Y′Z′ plane, also referred to as valgus-varus (FIG.         11C);     -   rotation in frontal flexing: this rotation corresponds to the         angle between two longitudinal vectors of the tibia and of the         femur in the X′Z′ plane (FIG. 11B);     -   shear of the knee corresponding to movement in translation         between the tibia and the femur along the three axes X, Y, and         Z, and in particular shear towards the front of the femur along         the axis X′; and     -   internal or external axial rotation of the tibia at the knee         when the foot and the ankle are held in a ski boot gives rise to         internal or external rotary movement through a given angle         relative to the horizontal longitudinal axis Y of the foot, of         the boot, and of the ski (FIG. 12).

The natural mobility of the knee depends on its frontal flexing angle in the X′Z′ plane (FIG. 11B) in axial rotation about Z′. Although the knee does not allow the tibia to rotate axially relative to the femur while the knee is in full extension, the amplitude of the external or internal axial rotation of the tibia that is allowed by the knee increases with increasing frontal flexing angle. Thus, with a frontal flexion angle of 90°, the internal axial rotation of the tibia is about 30°, correspondingly bringing the toe inwards, in combination with the adduction or abduction movement of the foot. The external axial rotation of the tibia is about 40° in external rotation. Although the locking of the ankle by the ski boot limits very strongly this amplitude of axial rotation of the tibia, it can still reach 20° in internal rotation and 25° in external rotation, giving a total amplitude of 45°.

The invention seeks to provide a protection device that does not impede the skier under normal skiing conditions, in particular during frontal flexing of the knee.

Various documents including U.S. Pat. No. 4,136,404, GB 2 436 799, or U.S. Pat. No. 6,524,110 describe systems for attaching to the boot. Those systems run along the lower limb, generally on either side, and they serve to stiffen the knee joint laterally. For that purpose, in all of those documents, a rigid top portion is hinged on a likewise rigid bottom portion, with the hinge being level with the knee. Those devices have generally not given rise to any use, or they have given rise to very restricted use with very particular sectors of the public, in particular with people suffering from certain kinds of minor disability.

In FR 2 679 931, GB 2 436 799, and WO 2009/092452, devices are described for fastening around the thigh, the tibia, and/or the knee and to the boot. Those devices have pivot connection type hinge systems at the knee since they seek to accompany frontal flexing of the femur relative to the tibia in the (substantially vertical) sagittal plane. However those devices do not prevent axial rotations of the femur and the tibia; at best they slow down axial rotations without controlling them and without preventing them.

Furthermore, in FR 2 679 931 and WO 2009/092452, the devices co-operate with a boot by means of pads that are inserted inside the collar.

Those devices are also complex to fabricate and awkward to install on the lower limb. Insofar as those devices include a hinge that is to be aligned with the skier's knee joint, they also need to be made to measure. It is thus observed that those products are not commercially available and are not used by competitors.

It should also be observed that the tibia can be fractured instead of spraining the knee or at the same time as spraining the knee. Excessive twisting or flexing of the leg while the foot and ankle are practically locked in the ski boot contributes to providing conditions that lead to a fracture of the tibia.

The object of the present invention is to provide a simpler device seeking essentially or mainly to limit shear in the plane of the tibia, in particular forward shear of the femur along the axis X′, and also seeking to limit relative axial rotations of the femur and tibia, but without interfering with frontal flexing at the knee and in particular without having recourse to a pivot connection at the knee and/or thus without having recourse to a device that needs to be connected to the thigh.

OBJECT AND SUMMARY OF THE INVENTION

A main object of the present invention is thus to limit the risk of injury to the ligaments and/or bones as a result of shear, in particular of forward shear of the femur along the axis X′, and as a result of relative axial or lateral rotation of the tibia or the femur while skiing, by means of a device that is simple and fabricate and to put on the lower limb, and that can be useful to a skier regardless of the pair of skis being used.

In the present invention, the device essentially comprises no more than a rigid shell provided with lateral flanges in its upper portion without any connection with the thigh and with means for connecting the shell to the collar so as to enable controlled limitation of rotation of the shell relative to the collar about the Z axis.

To do this, invention provides a device for protecting the knee joint of a skier, the device being for installing on a ski boot having a footwear portion surmounted by a collar, the device having first connection means designed to be fastened to the collar of the boot and a rigid shell designed to cover the front of the tibia of the skier, at least in part, the shell extending between a high portion for being situated level with knee and a low portion covering a portion of the collar of the boot, the shell including or supporting, on its high portion, rigid lateral flanges suitable for being put into contact with the knee on either side of the knee, being in contact at least with the condyles of the femur, the low portion of the shell being designed to cover part of the collar of the boot and including second connection means complementary to the first connection means of the collar of the boot and suitable for securing the shell to and above the collar of the boot in such a manner that the association of the first and second connection means provides a connection with limitation of movement in rotation of the shell relative to the boot about an axis of rotation substantially parallel to the axis of the collar of the boot.

With fabrication that is particularly simple, the invention makes it possible to limit the risk of injury associated with shear in the tibial plane, in particular shear and axial or lateral movements in rotation of the tibia or femur.

More particularly, the flanges completely cover the sides of the knee and the contact surfaces of the flanges, which press internally against the sides of the knee, cover at least the lateral surfaces of the knee that are in register with the femoral condyles.

More particularly, in horizontal section, the shell presents a forwardly bulging rounded profile shape (i.e. face convex towards the front) in such a manner as to cover the front of the knee and of the tibia and it extends over a portion only of the sides of the tibia, and in its low portion, over a portion of the sides of the collar. In practice, the shell may extend over a height of 30 centimeters (cm) to 55 cm, depending on the size of the skier.

The essential main function of the rigid shell is to support the flanges and to transfer the thrust forces of the knee against the flanges down to the boot and thus down to the binding holding the boot on the ski, since it is the bonding that determines the acceptable level of force, with the binding releasing the boot beyond a certain threshold.

The secondary function of the shell is to protect the front of the tibia against possible impacts.

The surfaces of the flanges thus perform an essential role because the transfer of force is maximized when the sides of the knee are pressing against the flanges if the thrust surface of the flange against the side of the knee is optimized.

Consequently, the thigh is held relative to the boot by using simple flanges that press against the condyles of the femur in association with a rigid tibia-protecting shell that is limited in the movements it can perform relative to the ski boot. This limitation very greatly reduces any risk of pathological movements in axial or lateral rotation between the tibia and the femur at the knee, and/or limits risks of shear, in particular forward shear of the femur along the axis X′.

It can be understood that said means for connecting the shell to the collar can allow the shell small degrees of freedom to move in rotation relative to the collar about an axis of rotation parallel to the longitudinal axis X of the ski and about an axis of rotation parallel to the transverse axis Y perpendicular to the longitudinal direction X of the ski, so as to avoid preventing and so as to track any frontal and lateral flexion movements of the tibia relative to the ankle in the boot and any frontal hyper-flexion movements of the leg rewards, it nevertheless being specified that the degree of freedom in rotation about the axis X for forward frontal movement of the shell is limited by the connection, if any, between the high portion of the shell and the tibia, as described below, and the degree of freedom in rotation about the axis X is limited by the overlap and the contact between the shell and the lateral sides of the collar.

According to an advantageous characteristic, the connection between the low portion of the shell and the collar of the boot provided by associating the first and second connection means provides a connection giving the shell at least one degree of freedom to move in rotation relative to the boot about an axis substantially parallel to the axis of the collar of the boot, the connection means being such that this movement in rotation of the shell relative to the boot is limited to a predetermined angular sector, preferably of less than 14°.

With this characteristic, the connection means provide a connection with at least one degree of freedom to move in rotation about an axis parallel to the axis of the tibia. The skier thus conserves a satisfactory amplitude of movement for skiing.

In contrast, axial movements in rotation between the tibia and the femur and also forward shear of the femur are limited by the presence of the shell.

According to a preferred characteristic, the device has means for adjusting the predetermined angular sector over which such movement in rotation is limited.

Connecting the device above the collar in accordance with the present invention presents the following advantages:

-   -   it does not interfere with the necessary small natural freedom         to move of the tibia inside the collar;     -   it enables the connection to be adjusted easily, in particular         concerning the amplitude of rotation about the axis of the         collar, thus making it easy to control the limit on movement in         rotation about the axis Z of the device relative to the collar;         and     -   it makes it possible to optimize the transfer of forces applied         against the device down to the binding of the boot on the ski.

This characteristic enables the skier to adapt the limit on rotation provided by the device to the skier's manner of skiing. This makes it possible to adjust the threshold beyond which axial rotation is blocked or at least braked by the device.

According to a particular characteristic of the invention, the device is such that the predetermined angular sector of rotation of the shell relative to the collar about an axis parallel to the Z axis of the collar is less than 14°, preferably less than 10°, and more preferably less than 7°. Thus, the amplitude of axial rotation between the tibia and the femur is limited respectively to less than 45°, advantageously to less than 30°, and preferably to less than 14°.

An angular sector in the range 45° to 30° serves to limit the risks of knee sprains in certain flexing positions while preserving good skiability. An angular sector in the range 30° to 14° makes it possible to obtain a wider spectrum of knee protection with minor detriment to the level of skiability. Such angular limitation makes it possible in particular to avoid reaching the breaking limit of the tibia. This provides increased protection for the tibia and for the knee joint, while leaving appreciable latitude of movement in certain skiing situations.

An angular limitation of 14° corresponds on average to the acceptable angular amplitude between the tibia and the femur. Knee protection is then optimized, since it is ensured that this limit is not reached whatever the behavior of the tibia. In general, it should be observed that the foot/ankle/tibia unit in a ski boot is constrained in such a manner that adduction and abduction are very limited. Movement of the foot relative to the tibia is thus very limited. In the event of an impact, the skier thus cannot benefit from this angular margin.

Furthermore, as a general rule, since the breaking limit of the femur is well above the limit for knee sprain, the risk of breaking the femur is small. In the event of this breaking limit of the femur being approached during an impact, the device of the invention may include a mechanical fuse so as to transfer the load to the knee even at the risk of that leading to a sprain.

In each of its embodiments, the device of the invention prevents, or under the worst circumstances brakes, movement of the thigh in rotation relative to the boot, i.e. the angle of the longitudinal axis of the femur relative to the axis of the ski.

This provides a significant limit on the risk of damage to the ligaments and/or the bones, which is achieved by the presence of the lateral flanges in contact with the condyles and by the limited movement of the shell relative to the boot, with this limitation being adapted as a function of the maximum angular amplitude allowed by the knee and as a function of the skiability preferences of the user.

In an advantageous embodiment of the invention, the first connection means comprise at least one guide part for installing in stationary manner on the collar of the boot, said guide part being suitable for co-operating with the second connection means of the shell that are complementary to said guide part so as to limit movement in rotation to the predetermined angular sector.

This embodiment involves installing at least one particular element on each boot for enabling the shell connection means to operate, and it makes it possible to achieve accurate control over the behavior of the shell relative to the boot. It is envisaged herein that these first connection means installed on the boot are elements that are present on the boot by default, such as a fastener or other element relative to which the shell takes up its position in order to have its movement in rotation limited.

With this characteristic, it should be observed that it is only ski boots that need to be provided beforehand with connection means in order to make use of the complementary connection means of the shell, without there being any need to modify the pair of skis in any way. Furthermore, a single shell can perfectly well be used by a given skier with any one of a plurality of pairs of boots, providing they are fitted with at least one guide part of this embodiment.

In a particular embodiment, the guide part comprises at least one rail for fastening to the collar of the boot so as to be substantially parallel to the axis of the boot, the second connection means constituting a groove that is complementary to the rail, the groove presenting a width that is greater than the width of the rail, thus allowing limited rotation about the axis that is substantially parallel to the collar of the boot.

Providing the groove is wider than the rail, the use of such a guide part forming the rail along the axis of the collar of the boot and co-operating with a groove carried by the connection means of the shell makes it possible for them to be relatively movable in rotation over an angle that is limited, and specifically over an angular sector of less than 14°, or advantageously less than 10°, or preferably less than 5°.

The width of the groove and the width of the rail are then determined as a function of the degree to which it is desired to limit rotation of the shell on the collar of the boot.

In another embodiment, the guide part has at least one groove for fastening on a lateral flank of the collar of the boot so as to be substantially parallel to the axis of the collar, the second connection means constituting a rail complementary to the groove, the groove presenting a width that is greater than the width of the rail, this width allowing limited rotation about the axis that is substantially parallel to the collar of the boot.

In this embodiment, it is the collar of the boot that carries the groove and the shell that carries a rail that can be allowed to move in the groove by the groove being wider than the rail.

In a particular characteristic, the difference between the width of the groove and the width of the rail varies along those structures, with this variable difference in width governing a front/rear flexing angle between the shell and the boot.

A variable difference in width between the two structures, the groove and the rail, serves to determine a front/rear flexing angle between the shell and the boot. When the high path of the groove is wider than the low path of the grove, while the rail is of constant width, then the shell can tilt forwards in free manner.

In another embodiment, the width of the groove and the width of the rail are constant, and the length of the rail is determined so as to determine a front/rear flexing angle between the shell and the boot. This embodiment enables the groove to pivot about the rail. The rail then acts as a pivot within the groove, which pivots about the rail.

In a second embodiment of the invention, the first and/or second connection means comprise at least one strap fastened firstly to the collar of the boot, and secondly to the shell in order to secure the shell to the collar of the boot.

This embodiment makes use either of the elasticity of the strap adapted as a function of the desired limitation on movement in rotation, or on a particular adjustment of the clamping of the strap which should then be inextensible, so as to allow a limited amount of movement in rotation of the shell relative to the boot. Such a particular adjustment of the clamping of the strap allowing a limited amount of movement in rotation over a predetermined angular sector is achieved by means of a mechanical element enabling the strap to be lengthened or shortened or enabling a predetermined length of the strap to be maintained. This type of device makes it easier to establish the connection between the shell and the collar.

Advantageously, the strap presents a particular length or a particular marking for adjustment purposes. For the guide part, the limitation is obtained by adjusting the width of the rail, whereas when a strap is used, the limitation is obtained by the ability of the strap to be extended, either because it is initially slack or because it is elastic.

Either the strap is suitable for limiting movement in rotation in both directions, or else the strap is associated with an abutment, or indeed two straps are used. Thus, in a particular embodiment, the first and second connection means comprise two straps, each of which has one end fastened to the collar and the other end to the shell, with the extent to which the straps can be extended limiting rotation in each of two opposite directions of rotation.

The use of two straps makes it possible to adjust the movement in rotation of the shell in both directions of rotation and thus to limit this movement in both directions of rotation.

In a variant embodiment, the connection between the low portion of the shell and the collar of the boot provided by associating the first and second connection means prevents the shell from moving in rotation relative to the boot about an axis substantially parallel to the axis of the collar of the boot.

Under such circumstances, and more particularly, said first and second connection means include non-elastic straps comprising two first straps fastened or suitable for being fastened in releasable manner on either side to the rear of the collar, and two second straps fastened or suitable for being fastened in releasable manner on either side of the shell, said first and second straps including complementary reversible connection means at their free ends suitable for reversibly securing the free ends of the first strap with the free ends of the second strap.

In a particular embodiment, the device also includes at least one abutment part for fastening to the collar of the boot, the shell also including a collar abutment element complementary to the abutment part of the collar and suitable for co-operating therewith in order to position the shell vertically along the tibia.

The abutment part serves to control proper vertical positioning of the shell relative to the tibia, and thus relative to the lower limb, in general manner.

In an embodiment, with the device in position at rest on the lower limb, the flanges apply force against the condyles substantially normally relative to the flanks of the thigh with a magnitude lying in the range ]0, 100 newtons (N)].

It is advantageous for the flanges to exert a non-zero force on the condyles of the femur so that any movement of the condyles relative to the flanges of the shell is minimized. Under such circumstances, only the degree of freedom to move in rotation about the axis Z is made available by the connection means connecting the shell to the collar of the boot and by the deformability of the material of the shell and the deformability of the soft tissues.

In the invention, in its broadest definition, the flange presents an outline over its rear portion and its top portion that is of arbitrary shape and the flange is of a size that is sufficient to cover the surface of the condyles of the femur.

More particularly, each flange presents a surface area suitable for covering the total surface area of the sides of the knee, preferably an area of at least 50 square centimeters (cm²), and preferably of at least 100 cm².

In a preferred embodiment, the flanges present an outline that is substantially in the form of a portion of an ellipse, in particular in the top and rear portions of the flanges. More particularly, the flanges present an outline that is substantially in the shape of at least half an ellipse over its top portion and over its rear portion.

Still more precisely, the major axis of the ellipse is inclined at an angle lying in the range 45° to 135° relative to the main longitudinal axis of the shell parallel to the rectilinear section of the front face of the shell in section on a longitudinal midplane of the shell.

Also preferably, the major axis of the portion of an ellipse is inclined at an angle lying in the range 70° to 110° and preferably equal to about 90° relative to said main longitudinal axis of the shell.

The preferred use of flanges having an elliptical outline is particularly suitable for providing lateral support to the lateral flanks of the thigh, with the orientation of the flanges enabling the skier's femur to be supported correctly in the skiing position without hindering the skier.

More particularly, the surface of each flange corresponds substantially to the surface of the top lateral portion of the shell situated above the bottom tangent of the ellipse parallel to the major axis of the ellipse and behind an axis parallel to the minor axis of the ellipse (and thus perpendicular to the major axis of the ellipse) situated about halfway along the major radius of the ellipse starting from the rectilinear section of the front face of the shell in a longitudinal midplane of the shell.

More particularly, the center of the ellipse is located substantially facing the condyle to within ±20 millimeters (mm) depending on the flexing at the knee. The bottom tangent to the ellipse parallel to the major axis of the ellipse is situated substantially facing the tibial plane when the major axis of the ellipse is at substantially 90° to said longitudinal axis of the shell parallel to the rectilinear section of the front face of the shell in section on a longitudinal midplane of the shell.

Still more particularly, the major axis of the ellipse is at least 5 cm long, and preferably of a length lying in the range 6 cm to 15 cm, and the minor radius of the ellipse is at least 2 cm long, and more particularly lies in the range 3 cm to 10 cm.

Still more particularly, the major axis of the ellipse is situated at 2 cm to 5 cm from the top end of the shell, and the center of the ellipse is situated at 5 cm to 10 cm from the rectilinear section of the front face of the shell in section on a longitudinal midplane of the shell.

Such dimensions for the ellipse and such an angle of inclination for the major axis of the ellipse lying in the range 70° to 110° enable the relationship between the flanges and the end of the bottom femoral epiphysis to be maintained in spite of the movement of the condyles during flexion/extension movements of the knee. This angle of inclination also corresponds to an intermediate angle of inclination between the positions of the thigh in movement or at rest.

More particularly, the flanges present surface areas suitable for covering the entire surface area of both sides of the knees, each flange preferably having an area of at least 50 cm², and more preferably of at least 100 cm².

Such a size for the flanges makes it possible to ensure good coverage of the femoral epiphysis, while ensuring that the device of the invention does not hinder the skier.

Also advantageously, the shell supports at least one element for connection to the tibia in its high portion, in particular a third strap having a self-gripping tape for holding it around the tibia.

Such a characteristic is the simplest way of holding the shell relative to the skier's tibia, other than securing it to the boot. It presents the advantage of being easy to implement and simple for the skier to handle.

In a preferred embodiment, the contact of the lateral flanges against the condyles of the femur takes place via ergonomic spacers inserted against the inside faces of the flanges. More particularly, the device has flanges that cooperate with or that include ergonomic spacers against the inside spaces of the flanges. This characteristic makes it possible to adapt a common shell to condyles having a variety of dimensions by interposing a variety of spacers. A common molded shell can thus be used for different sizes of device and also for making devices that are personalized. Under such circumstances, only the spacers need to be modified in order to obtain a variety of sizes or in order to obtain a personalized device.

The inside surfaces of the spacers may be made to measure so as to match the shape of the lower limb of a particular skier without hindering the flexion/extension movements of the knee.

Preferably, the flanges include ergonomic spacers on their inside surfaces that match in part the shape of the morphology of the sides of the knee without hindering frontal flexing of the knee. The area defined by the outline of a spacer thus corresponds to the area defined by the outline of the flange as described above and thus presents a value of at least 50 cm², and preferably of least 100 cm².

Advantageously, these ergonomic spacers may present a surface that is the result of melding the surfaces observed at the condyles of the skier for at least two preferred angular positions of the skier's lower limbs.

This personalization characteristic enables the device to be particularly agreeable to use in all skiing positions. Furthermore, this personalization of the protection device of the invention is most advantageous insofar as it serves to provide a very secure connection between the lateral flanges and the knee. This avoids any penalizing clearance being present at this point of the device, where such clearance would involve the femur being free to turn through an angle relative to the boot that is greater than the maximum angle determined by the device of the invention.

Advantageously, said flanges and/or spacers include linings of flexible material for coming into contact with the sides of the knee of the skier (S).

Still more particularly, each of said spacers comprises a rigid support covered in a lining of flexible material for coming into contact with the skier's knee, i.e. the portion that is to press against a side of the knee. The linings are arranged on the inside faces of the flanges, or preferably on the inside faces of the spacers, when spacers are used.

This characteristic increases skier comfort without degrading the effectiveness of the invention in terms of lateral movements in rotation.

More particularly, each of said spacers comprises a rigid support covered on its knee side with a lining of flexible material for coming into contact with the knee of the skier.

The lining may be made of a flexible material of the cellular material type (foam etc.), or of the gel type (silicone, etc.). The lining is thus advantageously made from at least one elastomer or plastics material of the ethylene vinyl acetate (EVA) type or of some other type that is optionally thermoformable and that presents thickness and density that are sufficient to provide comfort during movement of the lower limb while skiing. More particularly, the material may be a silicone gel in the form of a plate having thickness lying in the range 1 mm to 10 mm, and preferably in the range 2 mm to 5 mm.

The shell and the spacers are advantageously made of a rigid material that may be inorganic or organic, and it may be in a single piece or it may be in composite form, using materials selected from the following: magnesium, aluminum, titanium, metal alloys, polymers that may optionally be filled and that may optionally be reinforced, and resins that may optionally be composite, that may optionally be filled, and that may optionally be reinforced.

Advantageously, the composite is constituted by a matrix based on a thermosetting type resin such as epoxy, polyester, etc., or on a thermoplastic resin of the polyamide (PA) type or of the polycarbonate (PC) type or of some other type, together with at least one reinforcing material. The reinforcing material may be based on carbon fibers and/or on glass fibers and/or aramid fibers, e.g. on Kevlar® (trademark of the supplier of Dupont de Nemours) and/or on poly p-phenylene-2.6-benzobisoxazole (PBO)* (trademark of the supplier Toyobo Japan), and/or on PIPD M5 from the supplier Dupont de Nemours, and/or on ultra high molecular weight polyethylene (UHMWPE) DYNEEMA (trademark of the supplier DSM Holland). The reinforcing content in the composite lies in the range 0% to 70%. The reinforcement may be woven or knitted or braided, and it may be of the two-dimensional, or three-dimensional, or uni-dimensional type, or it may be constituted by cut fibers. Organic or inorganic fillers may be added to the matrix depending on the desired specifications. It is possible for the polymer material of the matrix and for the reinforcing fibers to contain carbon nanotubes in order to improve their mechanical characteristics. These materials generally serve to provide the shell and the spacers with good stiffness while also being light in weight and comfortable.

At least on a face of the lining that comes into contact with the lower limb, it is possible to apply a film or a fabric of the spandex or elastic type having a thickness of at least 10 micrometers (μm), the film or fabric being attached by adhesive to said surface in order to match the shape of the spacer.

The material of the film or fabric may present a low coefficient of friction. By way of example, the material may be made from polytetrafluoroethylene (PTFE) (e.g. of trademark Teflon in the name of Dupont de Nemours, USA). The thickness of the film or of the fabric is selected depending on the desired mechanical characteristics.

When the flanges or the spacers include a flexible lining over the portion that is to press against the sides of the knee, said connection means need not authorize any degree of freedom of the shell to move relative to the boot about an axis Z substantially parallel to the axis of the collar of the boot, since the condyles of the femur are held by the spacers positioned in the flanges and the spacers allow for a small amount of relative axial movement in rotation between the femurs and the tibias because the soft tissues between the condyles and the spacers deform when performing a movement in rotation. The angular sector is thus limited sufficiently by the shape and the clearance of the spacer in contact with the soft tissue over the condyles of the femur.

In general, the capacity of the device for adjustment and adaptation by using spacers enables the device to be adapted to the variability of skiers: age, sex, physical condition, muscle tone, contraction levels, etc. . . . . The expected levels of stress conditions are also corresponding parameters for adjusting the device: shear, lateral section, speeds, skier position, vertical acceleration, prestress between the device and the knee, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the present invention appear from the following description made with reference to the accompanying drawings which show an embodiment having no limiting character. In the figures:

FIG. 1 shows the principle of the invention;

FIGS. 2A to 2E show a first embodiment of the invention;

FIGS. 3A to 3E show a second embodiment of the invention;

FIGS. 4A to 4E show a third embodiment of the invention;

FIGS. 5A to 5C are diagrams showing the principle of a fourth embodiment of the invention;

FIGS. 6A and 6B show a preferred embodiment of the invention;

FIGS. 7A to 7C show spacers as used in the preferred embodiment of the invention;

FIG. 8 shows a device of the invention provided with spacers in the preferred embodiment of the invention;

FIGS. 9A and 9B are perspective views of a preferred embodiment without a boot (FIG. 9A) and fastened on a boot (FIG. 9B);

FIG. 10 shows a shell fitted with non-elastic straps;

FIGS. 11A to 11C show rotations between the femur and the tibia, axial rotation about the axis of rotation Z′ (FIG. 11A), frontal rotation about Y′ (FIG. 11B), and lateral rotation about X′ (FIG. 11C);

FIG. 12 shows the XYZ frame of reference relative to a boot; and

FIG. 13 shows variations in the angle of the femur relative to the longitudinal axis of the ski resulting from axial rotation of the tibia with and without the device of the invention, thereby showing the effectiveness of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

FIG. 1 is a diagram of the invention. This figure shows the bottom of the body of a skier S. The skier S has a ski boot 2, which is fastened to a ski 1 by means of a binding 1 a. The boot 2 has a footwear portion and a collar 21.

In FIG. 1, the foot P, the tibia T, and the femur F of the skier S can be seen. The femur F has condyles CF at its distal end. These condyles CF occupy a plurality of intermediate positions between two extreme positions that are shown in FIG. 1, as a function of the flexion position of the skier S.

In FIG. 1, the skier S is wearing a device of the invention. The device comprises a rigid shell 10 with a high portion 11 and a low portion 12. The low portion 12 has connection means for securing the shell 10 to the collar 21 of the boot 2. The high portion of the shell 10 has two lateral flanges that cover the condyles CF of the femur F on either side of the leg of the skier S, with this covering being provided by the lateral flanges in any flexion position of the skier S.

The lateral flanges present an outline 11 c forming a portion of an ellipse with a major axis X1 being oriented at about 70° relative to Z′. This orientation lies in the range 45° to 135° and serves to obtain satisfactory pressure on the condyles of the femur and thus good retention of the femur for axial and lateral rotations relative to the tibia. The embodiments described below show preferred orientations for the lateral flanges lying in the range 70° (FIG. 1) to 90° (FIG. 10).

In FIG. 10, the height H of the shell lies in the range 300 mm to 600 mm, and more particularly in the range 350 mm to 500 mm, depending on the size of the skier.

In FIG. 10, the outline 11 c of the top and rear portions of the flange presents a shape including substantially an upper half-ellipse and a lateral half-ellipse forming parts of the same virtual ellipse of center C1 that is substantially in register with the condyle CF. The major axis X1 of the ellipse is substantially perpendicular to the longitudinal main axis of the shell and perpendicular to the rectilinear section of the front face limit 10 a of the shell in a section on a longitudinal midplane of the shell. Each flange is defined by a bottom tangent X2 of said ellipse that is substantially in register with the tibial plane X′Y′ parallel to the major axis X1 of the ellipse. The major radius R of the ellipse is 65 mm and the minor radius r of the ellipse is 50 mm. The center C1 of the ellipse is situated at a distance d=68 mm from the front face limit 10 a of the shell in a section on the longitudinal midplane of the shell. The total area of each flange 11 a, 11 b as defined by the surface situated above the bottom tangent line X2 to the ellipse that is parallel to X1 and behind an axis Z2 parallel to the minor axis Z1 of the ellipse is situated at about ½ R from the rectilinear section of the front face 10 a of the shell in section on the longitudinal midplane of the shell, and said surface area is about 100 cm².

Thus, the lateral flanges completely cover the distal femoral epiphysis, each bearing on opposite sides of the end of the femur, i.e. against the femur condyles CF on either side of the knee. They serve to limit lateral rotation of the femur F relative to the foot P of the skier S.

Advantageously, the force with which the flanges press against the condyles is adjustable. The flanges apply a force on the condyles substantially normal to the flanks of the thigh with a magnitude lying in the range ]0, 100N].

FIGS. 2A and 2E show a first embodiment of the invention. These figures are respectively a face view of the device 10, a side view, a plan view, and after being put into place on a ski boot, a side view and a perspective view.

The device 10 has two lateral flanges 11 a and 11 b for placing on either side of the skier's knee so as to clamp onto the femur condyles CF. The lateral flanges 11 a and 11 b may themselves be in contact with the garment covering the condyles CF or it may be in contact with the condyles CF via spacers, as described below.

The bottom portion 12 of the device 11 has second connection means 12 a and 12 b. The second connection means 12 a and 12 b of the shell are complementary to the first connection means referenced 22 a and 22 b, forming guide parts on the collar 21 of the boot 2. Such first connection means 22 a and 22 b are shown in FIGS. 2D and 2E.

In the embodiment shown in FIGS. 2B-2E, the first connection means 22 a and 22 b constitute a guide part made up of two elements referenced M1 and M2 and forming jaws. The second connection means 12 a and 12 b are constituted by two tongues referenced La and Lb, each sliding between the two pairs of jaws M1 and M2 placed on either side of the collar 21 of the boot 2.

It should be observed at this point that it is possible to envisage using only a single pair of jaws M1, M2 placed on one of the sides of the collar 21 of the boot 2, preferably the outside. This pair of jaws associated with a tongue of the type shown in FIG. 2B does indeed suffice to limit any rotation of the shell relative to the boot providing the high portion of the shell is also secured to the skier's tibia by means of a single self-gripping tape 15 situated immediately beneath said high portion 11 for the purpose of surrounding the tibia, as shown in FIG. 9B. Nevertheless, the use of two pairs serves to make the behavior of the shell more robust and in particular serves to prevent it from pivoting as a whole about the tongue La.

Since the width of the open space between the two jaws M1 and M2 is greater than the width of the tongue La, the tongue can move a little, and this movement causes a limited angular sector of the shell 10 to move in rotation. Thus, the fastening of the shell 10 on the collar 21 of the boot 2 provides a degree of freedom in rotation relative to the boot 2 over an angular sector that is predetermined and limited. It may be observed at this point that the jaws M1 and M2 may also be positioned so that the tongue is prevented from moving in rotation. Under such circumstances, the shell is maximally secured to the boot and knee protection is at its best. In the event of relative axial rotation of the tibias giving rise to angular displacement of the longitudinal axis of the femur relative to the axis of the ski, the knee comes to abut against the lateral flanges 11 a and 11 b and prevents the knee being twisted. Nevertheless, this can reduce skiability.

It can thus be understood at this point that it is advantageous to use embodiments of the invention that allow a limited amplitude of rotation to be obtained. The use of a small angular sector over which the shell 10 is free to move in rotation is advantageous from a skiability point of view. Such a freedom to move in rotation over a limited angular sector does not significantly degrade the protection conferred by the invention, since the joints in question have a certain tolerance margin before being damaged.

In FIGS. 2D-2E, the jaw-forming elements M1 and M2 are fastened relative to the boot 2. It should be observed in this example that at least one of these elements M1 and M2 could be slidably mounted in order to be able to adjust the lateral space in which the second connection means 12 a and 12 b of the shell can move. This thus makes it possible to adjust the angular sector over which the tongues La and Lb of the second connection means 12 a and 12 b of the shell 10 can move in the first connection means 22 a and 22 b fastened to the collar 21 of the boot 2.

FIG. 3 show a second embodiment of the invention.

In this embodiment, the shell 10 has two lateral flanges 11 a and 11 b on its high portion 11 that is comparable with the high portion of the above-described embodiment. The shell 10 has second connection means 12 a and 12 b that are different from those of the above-described embodiment. These connection means 12 a and 12 b have orifices for attaching a strap 13 shown in FIGS. 3D and 3E. The strap 13 is typically riveted in the orifices 12 a and 12 b.

The strap 13 is also attached to a support referenced 23 that is mounted on the boots 2, this support 23 constituting first connection means fastened to the collar 21 of the boot.

The slackness of the adjustment of the strap 13 or its pre-calibrated elasticity make it possible to limit rotation of the shell 10 relative to the boot 2 containing the foot of the skier S.

FIG. 3 show a single lateral strap for reasons of simplicity in drawing. It can be understood that it is necessary to use two straps, one on either side of the boot 2, in order to limit rotation in both directions. Nevertheless, it should be observed in this example that a single strap fastened level with the second connection means 12 a and 12 b of the shell as shown in FIG. 3 could be used with first connection means fitted to the boot 2 in order to adjust completely movement in rotation of the shell 10 relative to the boot 2.

It should also be observed that it is possible to use a strap for movement in rotation of the shell in one direction relative to the boot 2 and other means of the type represented by the guide part shown in the above-described embodiment for limiting movement in rotation in the opposite direction. Under such circumstances, a single guide part, e.g. having two jaws M1 and M2, would be needed for performing the invention.

FIG. 4 shows a third embodiment that differs slightly from the second embodiment. This embodiment uses a strap 13 to secure the low portion 12 of the shell 10 to the boot. In this embodiment, the strap is fastened in a slot 12 a, however its function is substantially identical to that performed by the strap 13 in FIG. 3.

Nevertheless, it can be understood that the strap 13 cannot genuinely prevent upward movement of the shell 10. This movement would interfere with operation of the invention and could be troublesome for the skier.

Thus, an abutment part 24 is placed on the boot 2. This abutment part 24 is complementary to an abutment element 14, in this example an orifice in the shell 10. The abutment part 24 serves to position the shell 10 relative to the collar 21 of the boot 2 in a vertical direction so as to prevent the shell moving vertically along the skier's tibia.

Such an abutment part 24 is also used in the embodiment of FIG. 5. These figures show a guide part 22 a suitable for being fastened directly on a lateral side of the collar 21 of the boot 2.

The guide part 22 a has a rail referenced R that is terminated by a second abutment part 25, complementary to the abutment part 24. It can be understood that the abutment part 25 prevents any downward movement of the shell 10 having part of its low portion 12 shown in FIGS. 5B and 5C. This low portion 12 of the shell 10 includes a slideway or groove G that is positioned relative to the rail R by sliding along the rail.

In the perspective view of FIG. 5C, it can be seen that the rail R is of a width such that the slideway or groove G can move forwards and rearwards through a greater or lesser angle. This flexing angle depends on the clearance present between the rail R and the slideway G. This enables satisfactory skiability to be conserved.

The spacing between the rail R and the slideway G is thus advantageously adjustable in order to provide control over a few degrees of movement in rotation of the system about the axis of the boot 2.

FIG. 6A shows the shell 10 associated with a single support for a spacer 30 that is useful for positioning the shell 10 relative to the leg of the skier S. FIG. 6B shows the FIG. 6A device installed on a skier's leg, which leg is shown in two extreme positions of flexing.

FIGS. 7A to 7C are various perspective views of the functional lateral portions of the spacer 30, which portions are referenced 30 a and 30 b. It can be seen that the surfaces of the functional portions of the spacer 30 are molded to have shapes that are quite particular.

These shapes correspond to melding of the surfaces observed over the condyles CF of the femur F between two preferred positions, which may for example be the positions of extreme flexing of the thigh of the skier S as shown in FIG. 6B.

These shapes correspond to melding of the surfaces observed over the condyles CF of the femur F between two preferred positions, which may for example be the positions of extreme flexing of the thigh of the skier S as shown in FIG. 6B.

This maximizes comfort for the skier who, between the two extreme positions, conserves lateral pressure that matches the skier's morphology, i.e. that is personalized, against the condyles of the femur. The functional portions 30 a and 30 b of the spacer 30 are thus not symmetrical, since the sides of the knee have shapes and deformations that are quite distinct during their flexing movements. In contrast, symmetry may exist between the corresponding functional portions for the two knees.

FIG. 8 shows a preferred embodiment in which the shell 10 is provided with two functional portions 30 a and 30 b. This is the shell adapted for a right knee. The shell for the left knee is advantageously symmetrical to the shell shown in FIG. 8.

In this figure, the shell 10 has a central abutment orifice 14 and grooves G, in this example oblong orifices. These grooves G co-operate with an abutment or a rail as shown in FIG. 5 in order to allow angularly limited movement in rotation.

The shell 10 of FIG. 8 also has through holes or orifices O for receiving a mechanical element that fastens a strap 13. The strap 13 is a strap of the type shown in FIGS. 3 and 4. Under such circumstances, the two types of limitation on movement in rotation of the shell of the invention coexist within a single article.

Nevertheless, a particularly simple and preferred version uses only one strap 13 on either side attached permanently to the shell or to the heel of the boot by means of a hook 23, as shown in FIGS. 9. Under such circumstances, it is the adjustment of the strap received in the orifices O that alone determines the angular sector over which the shell can pivot relative to the boot.

In FIGS. 9A, 9B, and 10, there can be seen an embodiment of the shell with said means for fastening the shell to the collar in which said first and second connection means comprise non-elastic straps, made up of two first straps 13 a that are releasably fastened or suitable for being releasably fastened to an element 23 on either side of the rear portion of the collar, and two second straps 13 b, 13 b-1, 13 b-2 that are releasably fastened or suitable for being releasably fastened (in an orifice O) on either side of the shell, said first and second straps 13 a and 13 b having complementary connection elements 13 c, 13 d at their free ends that are suitable for reversibly connecting the free ends of the first strap 13 a with the free ends of the second strap 13 b.

FIG. 13 shows a model of the axial internal rotation of the tibia leading to angular movement in the horizontal plane between the femur and the axis of the tibia that is plotted in degrees relative to time for a skier wearing a device of the invention (curve AKG) and for a skier not wearing a device of the invention (curve SKG).

It can be seen that the internal rotation is very greatly reduced when the device of the invention is worn by the skier. Although it is particularly simple to fabricate, and also to install on a skier's leg, the device of the invention provides significant improvements in terms of accidents leading to knee sprain associated with this type of relative axial rotation between the tibia and the femur.

Because of its simplicity and its low production cost, the invention makes it possible to reach a large public. Models may have standardized lateral flanges preferably associated with a spacer having functional surfaces calculated on the basis of an average of the femur condyle surfaces observed in the population between the two extreme positions of flexing under skiing conditions.

Nevertheless, for smaller markets, typically in the field of competition, the invention also makes it very easy to personalize the protection device of the invention. For this purpose it suffices to use a shell of the same kind as is used for consumer goods in association with functional spacer portions specifically designed and shaped to correspond with the particular morphology of a ski champion, for example.

Finally, it should be observed that various embodiments may be provided on the principles of the invention as defined in the claims below. In particular, the movement in rotation of the shell relative to the boot may be limited to a limited angular sector by various connection means performing the functions needed in the invention. 

1. A device for protecting the knee joint of a skier, the device being for installing on a ski boot having a footwear portion surmounted by a collar, the device having first connection means designed to be fastened to the collar of the boot and a rigid shell designed to cover the front of the tibia of the skier, at least in part, the shell extending between a high portion for being situated level with the skier's knee and a low portion covering a portion of the collar of the boot, the shell including or supporting, on its high portion, rigid lateral flanges suitable for being put into contact with the knee on either side of the knee, being in contact at least with the condyles of the femur of the skier, the low portion of the shell being designed to cover part of the collar of the boot and including second connection means complementary to the first connection means of the collar of the boot and suitable for securing the shell to and above the collar of the boot in such a manner that the association of the first and second connection means provides a connection with limitation of movement in rotation of the shell relative to the boot about an axis of rotation substantially parallel to the axis of the collar of the boot.
 2. The device according to claim 1, characterized in that the connection between the low portion of the shell and the collar of the boot provided by associating the first and second connection means provides a connection giving the shell at least one degree of freedom to move in rotation relative to the boot about an axis substantially parallel to the axis of the collar of the boot, the connection means being such that this movement in rotation of the shell relative to the boot is limited to a predetermined angular sector of less than 14°.
 3. The device according to claim 2, characterized in that the flanges cover the sides of the knee completely, each flange presenting a surface area of at least 50 cm².
 4. The device according to claim 1, characterized in that, in horizontal section, the shell presents a forwardly bulging rounded profile shape in such a manner as to cover the front of the knee and of the tibia and it extends over a portion only of the sides of the tibia, and in its low portion over a portion of the sides of the collar.
 5. The device according to claim 1, characterized in that the first connection means comprise at least one guide part for installing in stationary manner on the collar of the boot, said guide part being suitable for co-operating with the second connection means of the shell that are complementary to said guide part so as to limit movement in rotation to the predetermined angular sector.
 6. The device according to claim 1, characterized in that the connection between the low portion of the shell and the collar of the boot provided by associating the first and second connection means prevents the shell from moving in rotation relative to the boot about an axis substantially parallel to the axis of the collar of the boot.
 7. The device according to claim 1, characterized in that the first and/or second connection means comprise at least one strap fastened firstly to the collar of the boot, and secondly to the shell in order to secure the shell to the collar of the boot.
 8. The device according to claim 6, characterized in that said first and second connection means include non-elastic straps comprising two first straps fastened or suitable for being fastened in releasable manner on either side to the rear of the collar, and two second straps fastened or suitable for being fastened in releasable manner on either side of the shell, said first and second straps including complementary reversible connection means at their free ends suitable for reversibly securing the free ends of the first strap with the free ends of the second strap.
 9. The device according to claim 1, characterized in that each of the flanges presents an outline that is substantially in the form of a portion of an ellipse over the top portion and over the rear portion of said outline of the flange, the major axis of the ellipse being inclined at an angle lying in the range 45° to 135° relative to the main longitudinal axis of the shell parallel to the rectilinear section of the front face of the shell in section on a longitudinal midplane.
 10. The device according to claim 9, characterized in that said major axis of the ellipse is inclined at an angle lying in the range 70° to 110° relative to said main longitudinal axis of the shell, and the surface of the flange corresponds substantially to the top lateral portion of the shell situated above the bottom tangent of the ellipse parallel to the major axis of the ellipse and behind an axis parallel to the minor axis of the ellipse situated about halfway along the major radius of the ellipse starting from the rectilinear section of the front face of the shell in a longitudinal midplane of the shell.
 11. The device according to claim 1, characterized in that the shell supports at least one element for connection to the tibia in its high portion, comprising a strap.
 12. The device according to claim 1, characterized in that the contact of the lateral flanges against the condyles of the femur takes place via ergonomic spacers inserted against the inside faces of the flanges.
 13. The device according to claim 1, characterized in that the flanges cooperate with or include said spacers that in part match the shape of the morphology of the sides of the knee without hindering frontal flexions of the knee.
 14. The device according to claim 1, characterized in that said flanges and/or spacers include linings of flexible material for coming into contact with the knee of the skier.
 15. The device according to claim 14, characterized in that each of said spacers comprises a rigid support covered on its knee side with a lining of flexible material for coming into contact with the knee of the skier.
 16. The device according to claim 3, wherein the surface area is at least 100 cm².
 17. The device according to claim 10, wherein the angle is 90°. 